The CSR and RSA key are two components involved in the generation of an SSL certificate. These are provided as blocks of encrypted text and can be confused with one another; however, they are quite different and fill very different roles.
What is a CSR?
A Certificate Signing Request, or CSR, is a block of encrypted text which contains information that will be included in the SSL certificate itself. This includes data such as the organization name, domain name, locality and country. It also includes the public keys for the SSL certificate.
The CSR is generated by the server on which the SSL certificate will be installed, and is then used by the SSL certificate provider to create the SSL certificate itself.
If you are renewing your certificate or if your certificate is expired, then you will need to request a new CSR.
What is an RSA Key?
An RSA key is the private encryption key that will be used to protect sensitive information. As the name implies, an encryption key is used to encode and decode information securely.
Currently, HostGator uses a 2048-bit RSA key.
The RSA key is generated by the server which the SSL certificate will be installed upon. You will receive the RSA Key when the CSR Request is submitted.